Polymers containing bioactive glass with antimicrobial effect

ABSTRACT

The invention relates to a bioactive glass as additive for polymers, wherein the bioactive glass contains 40 to 90 percent by weight SiO 2 ; 4 to 45 percent by weight CaO; 0 to 35 percent by weight Na 2 O; 2 to 16 percent by weight P 2 O 5 ; 0 to 25 percent by weight CaF 2 ; 0 to 10 percent by weight B 2 O 3 ; 0 to 8 percent by weight K 2 O and/or 0 to 5 percent by weight MgO. The invention also relates to a polymer comprising bioactive glass, wherein 1 to 30 percent by weight of bioactive particles are contained in relation to its overall weight The invention further relates to the utilization of bioactive glass in households, packaging, food processing, sealing materials, garments, medicine, sanitation, automotive industry, building industry, plastic coatings and adhesives.

[0001] The invention relates to polymers containing an antibacterial andfungicidal bioactive glass as additive.

[0002] It is known that an antibacterial and fungicidal action can beachieved in polymers by the introduction of aluminosilicates, such aszeolites, cf. JP-A-3145410; JP-A-1164721, U.S. Pat. No. 6,071,542,JP-A-03145410, U.S. Pat. No. 5,698,212, U.S. Pat. No. 5,939,087, U.S.Pat. No. 5,827,524, EP-A-732052. The aluminosilicates contain smallquantities of heavy metal ions with an antimicrobial action, such as Ag,Cu, Zn, Sn, Pb, Bi, Fe, Cr. The actual antibacterial action is in thiscase derived from the heavy metal ions which are introduced, the zeoliteserving only as a matrix without having any antibacterial or fungicidalaction of its own. Furthermore, it is known that an antimicrobial actioncan be achieved by introducing silver into glass, cf. JP10158037,JP6100329. Heavy metals (such as for example Ag, Cu, Zn, Sn, Pb, Bi, Fe,Cr) may cause reactions in the body, even reactions which are as seriousas allergic reactions or damage to organs.

[0003] Organic, active, microbially acting compounds, such as triclosan(trichlorohydroxydiphenylether) or paraben (p-hydroxybenzoates) maylikewise lead to health problems and allergic reactions. Moreover,organic compounds are difficult to fix locally.

[0004] Moreover, it is known that an antibacterial and fungicidal actioncan be achieved in polymers by the introduction of organometalsubstances. In this case, by way of example, organomercury and/ororganocopper compounds are used; in about 70% of the products, theaction is based on arsenic. These substances are harmful on account ofthe toxicological and ecological dangers which they present.

[0005] The object of the present invention is to provide anantibacterially and fungicidally acting additive for polymers withoutharmful side effects.

[0006] The object is achieved by a bioactive glass as additive forpolymers, the bioactive glass containing

[0007] 40 to 90% by weight of SiO₂,

[0008] 4 to 45% by weight of CaO,

[0009] 0 to 35% by weight of Na₂O,

[0010] 2 to 16% by weight of P₂O₅,

[0011] 0 to 25% by weight of CaF₂,

[0012] 0 to 10% by weight of B₂O₃,

[0013] 0 to 8% by weight of K₂O and/or

[0014] 0 to 5% by weight of MgO.

[0015] The bioactive glass according to the invention has anantibacterial and fungicidal action in plastics and is at the same timetoxicologically harmless; in particular, the bioactive glass does notcontain any toxic heavy metals.

[0016] It has emerged that a bioactive glass which containssubstantially only SiO₂, P₂O₅, Na₂O and CaO is a suitable additive forpolymers. The bioactive glass satisfies the requirement of beingtoxicologically harmless, since it does not contain any heavy metals ororganically active compounds whatsoever.

[0017] The glass composition influences the release of ions. Exchange ofions with the aqueous environment results in an antibiotic action which,depending on the ionic fraction, can be set from biostatic to biocidal.A possible sustained action should also be noted, since the release ofthe ions can be controlled by varying the glass composition.

[0018] A preferred configuration of the invention is a bioactive glassas additive for polymer, the bioactive glass containing

[0019] 40 to 60% by weight of SiO₂,

[0020] 10 to 30% by weight of CaO,

[0021] 10 to 35% by weight of Na₂O,

[0022] 2 to 8% by weight of P₂O₅,

[0023] 0 to 25% by weight of CaF₂,

[0024] 0 to 10% by weight of B₂O₃,

[0025] 0 to 8% by weight of K₂O and/or

[0026] 0 to 5% by weight of MgO.

[0027] This glass composition, as an additive to polymers, achieves verygood results in terms of the antibacterial and fungicidal action.

[0028] A further preferred configuration of the invention is a bioactiveglass as an additive for polymers in which the glass particles have amean particle size of less than 100 μm. This particle size increases thereactivity.

[0029] A particularly preferred configuration of the invention is abioactive glass as additive for polymers in which the glass particleshave a mean particle size of less than 5 μm. This particle size greatlyincreases the reactivity.

[0030] A very particularly preferred configuration of the invention is abioactive glass as additive for polymers in which the glass particleshave a mean particle size of less than 2 μm, preferably less than 1.5.This particle size increases the reactivity to a relatively greatextent.

[0031] A further configuration of the invention is a bioactive glass asadditive for polymers, in which the bioactive glass additionallycontains Ag⁺, Cu⁺, Cu²⁺ and/or Zn⁺. With this composition, a synergisticenhancement of the biocidal action is obtained.

[0032] The invention also provides a polymer containing bioactive glasswhich, based on its total weight, contains 1 to 30% by weight ofbioactive glass particles.

[0033] A preferred configuration of the invention is a polymercontaining bioactive glass which, based on its total weight, contains 1to 10% by weight of bioactive glass particles.

[0034] The invention also provides a polymer as carrier material forbioactive glass which, based on the total weight, contains 30 to 90% byweight of bioactive glass.

[0035] A preferred configuration of the invention is a polymer ascarrier material which, based on the total weight, contains 30 to 50% byweight.

[0036] The invention also provides for the use of the bioactive glass asan antimicrobial polymer additive.

[0037] A preferred configuration of the invention is the use of thebioactive glass in the domestic sector, in packaging, in foodprocessing, in sealing compounds, in clothing, in the medical sector, inthe sanitary sector, in the automotive sector, in the constructionsector and as a plastic coating or adhesive bonding.

[0038] In many application areas for polymers, an antibacterial andfungicidal action is desired, but this action should not generally beachieved by the use of toxic heavy metals. These include applications inthe following fields: silicones used in the first-aid sector, in sealingcompounds, polyacrylates in bottles for babies, in the food processingand packaging sector, in domestic goods, in the clothing sector, formedical applications, such as protective gloves, catheters or woundbandages, plastic coatings, such as for handles or wash basins, plasticbrushes, such as toothbrushes, natural rubber, latex such as mattresses.

[0039] Abrasive applications, in which new surfaces containing bioactiveglass are constantly created, are particularly advantageous.Applications in which the bioactive glass additive, in addition to theantimicrobial action, also has additional functions, such as that of astabilizer for setting the mechanical properties, viscosity and duringprocessing, are also advantageous.

[0040] Without thereby restricting the use of bioactive glasses in thepolymer sector, there are polymers which are especially suitable forbioglass to be added to. These include in particular PGA biodegradablepolymer, LGA biodegradable polymer, polyamides, polycarbonates,polyesters, polyimides, polyurea, polyurethanes, organic fluoropolymers,polyacrylamides and polyacrylic acids, polyacrylates, polymethacrylates,polyolefins, polystyrenes and styrene copolymers, polyvinyl esters,polyvinyl ethers, polyvinylidene chloride, vinyl polymers,polyoxymethylenes, polyaziridines, polyoxyalkylenes, polyethylene,synthetic resins (alkyl resins, amino resins, epoxy resins, phenolicresins, unsaturated polyester resins), electrically conductive polymers,high-temperature polymers, inorganic polymers, polyphenylene oxide,silicones or the biopolymers: collagen, fibrin, chitin, chitosan,cellulose, cellulose ester, cellulose ether, enzymes, gelatin, naturalresins, nucleic acids, polysaccharides, proteins, silk, starch, wool.

[0041] The action of the bioactive glass in polymers is in theantibacterial and fungicidal field, in the setting of the viscosity, inthe improvement to mechanical properties, as stabilizers and to protectthe polymer from fungal attack and destruction of the polymer.

[0042] Bioactive glasses, unlike conventional glasses, are distinguishedby the fact that they are reactive in an aqueous medium and can form ahydroxyl apatite layer at their surface.

[0043] If bioactive glasses come into contact with water or a bodyfluid, they are distinguished by special reactions, in which, inparticular, inter alia sodium and calcium ions of the glass are replacedby H+ions from the solution in the form of a cation exchange reaction,with the result that a surface which includes silanol groups is formed,at which sodium hydroxide and calcium hydroxide accumulate. The increasein the hydroxide ion concentration at the glass surface leads to thesiloxane compound being released and therefore to further silanol groupsor to ion exchange possibilities.

[0044] The molar ratio of calcium oxide to phosphorus oxide ispreferably >2 and in particular >3 and is preferably <30, in particular<20, ratios of <10 being particularly preferred.

[0045] Polymer additives which contain bioactive glass particles whichinclude SiO₂, CaO, Na₂O, P₂O₅, CaF₂, B₂O₃, K₂O and/or MgO areparticularly preferred.

[0046] In both of the types of bioactive glasses described above, thephosphorus oxide content is preferably at least 2% by weight, inparticular at least 4% by weight.

[0047] Bioactive glass itself is a material which is approximatelyround, such as for example sand. Particles of this type may be of a sizeof up to approx. 0.5 to 1 mm but are preferably significantly smaller.Standard particle sizes are ≦400 μm, and in particular ≦200 μm, andparticle sizes of ≦100 μm, preferably ≦90 μm, and in particular ≦60 μmand ≦20 μm, have proven particularly expedient. A preferred grainfraction has a diameter d₅₀ of ≦10 μM, preferably ≦5 μm, particularlypreferably ≦2 μm. The higher the ratio of surface area to weight orvolume, the higher the antimicrobial action of the particles becomes.

[0048] Preferred plastics are all polymers in which the plastic itselfis to be protected from attack from bacteria and fungi or is in contactwith moisture and is to have a bacteriostatic, bactericidal and/orfungicidal action.

[0049] The antimicrobial polymer additive according to the invention ispreferably present in an amount of up to 25% by weight, in particular upto 15% by weight, based on the polymer. However, upper limits of 10% byweight or 7% by weight are preferred, and 5% by weight is particularlypreferred. Lower limits are 0.01% by weight, in particular 0.1% byweight, with 0.5% by weight-or 1% by weight being particularly preferredas the lower active quantity.

[0050] The polymer can also be used as carrier material for bioglass. Inthis case, bioglass is present in the polymer matrix in an amount offrom 10 to 90% by weight, preferably 30 to 70% by weight, 30-50% byweight being particularly preferred.

[0051] The desired antimicrobial action is achieved with the polymeradditives according to the invention even without further additives, inparticular without the addition of additives which release Ag⁺, Cu⁺,Cu²⁺ and/or Zn⁺. The antimicrobial action of the polymer additiveaccording to the invention can be synergistically enhanced by theaddition of further sterilizing and/or germicidal agents or ofantibiotic agents.

1. A bioactive glass as an additive for polymers with an antimicrobialaction, the bioactive glass containing 40 to 90% by weight of SiO₂, 4 to45% by weight of CaO, 0 to 35% by weight of Na₂O, 2 to 16% by weight ofP₂O₅, 0 to 25% by weight of CaF₂, 0 to 10% by weight of B₂O₃, 0 to 8% byweight of K₂O and/or 0 to 5% by weight of MgO.
 2. The bioactive glass asadditive for polymers with an antimicrobial action as claimed in claim1, the bioactive glass containing 40 to 60% by weight of SiO₂, 10 to 30%by weight of CaO, 10 to 35% by weight of Na₂O, 2 to 8% by weight ofP₂O₅, 0 to 25% by weight of CaF₂, 0 to 10% by weight of B₂O₃, 0 to 8% byweight of K₂O and/or 0 to 5% by weight of MgO.
 3. The bioactive glass asadditive for polymers with an antimicrobial action as claimed in claim 1or 2, in which the glass particles have a mean particle size of lessthan 100 μm.
 4. The bioactive glass as additive for polymers with anantimicrobial action as claimed in at least one of claims 1 to 3, inwhich the glass particles have a mean particle size of less than 5 μm.5. The bioactive glass as additive for polymers with an antimicrobialaction as claimed in at least one of claims 1 to 4, in which the glassparticles have a mean particle size of less than 2 μm.
 6. The bioactiveglass as additive for polymers with an antimicrobial action as claimedin at least one of claims 1 to 5, wherein the bioactive glassadditionally contains Ag⁺, Cu⁺, Cu²⁺ and/or Zn⁺.
 7. A polymer with anantimicrobial action containing bioactive glass as claimed in at leastone of claims 1 to 6, in which, based on its total weight, from 1 to 30%by weight of bioactive glass particles are present.
 8. The polymer withan antimicrobial action containing bioactive glass as claimed in claim7, in which, based on its total weight, from 1 to 10% by weight ofbioactive glass particles are present.
 9. A polymer with anantimicrobial action as carrier material for bioactive glass as claimedin at least one of claims 1 to 6, in which, based on the total weight,the bioactive glass content is from 30 to 90% by weight.
 10. The polymerwith an antimicrobial action as carrier material as claimed in claim 9,in which, based on the total weight, the bioactive glass content is from30 to 50% by weight.
 11. The use of the bioactive glass as claimed in atleast one of claims 1 to 10 as an antimicrobial polymer additive. 12.The use of the bioactive glass as claimed in claim 11 in the domesticsector, in packaging, in food processing, in sealing compounds, inclothing, in the medical sector, in the sanitary sector, in theautomotive sector, in the construction sector and as a plastic coatingor adhesive bonding.